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This paper investigates of a kind of five-phase dual-rotor permanent-magnet synchronous motor (DRPMSM), which contains dual rotors and a single stator. This kind of motor has the potential advantages of high power density, high reliability and high efficiency, which make it more appropriate for using in electric vehicles (EVs). In order to evaluate the most suitable power level for this kind of structure, the electromagnetic, the thermal and the mechanical characteristics are investigated in this paper. The length to diameter ratio of motors is researched to obtain the highest power density and then the optimum ratio is obtained. Based on the optimum ratio, the thermal characteristics are researched under natural condition and forced-air cooling condition with different wind speeds. In addition, the mechanical characteristics are analyzed under no-load and different loads conditions, respectively. All of the results are analyzed by two-dimension (2-D) and three-dimension (3-D) finite element method (FEM) simulation, which provide a good reference to select suitable power level for this kind of motor structure. Finally, a DRPMSM prototype is manufactured and tested. The experimental results effectively verify the FEM results.

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Thermal analysis is exceptionally important for operation safety of axial permanent magnet couplings (APMCs). Combining a finite element method (FEM) with a lumped-parameter thermal network (LPTN) is an effective yet simple thermal analysis strategy for an APMC that is developed in this paper. Also, some assumptions and key considerations are firstly given before analysis. The loss, as well as the magnetic field distribution of the conductor sheet (CS) can be accurately calculated through FEM. Then, the loss treated as source node loss is introduced into the LPTN model to obtain the temperature results of APMCs, where adjusting conductivity of the CS is a necessary and significant link to complete an iterative calculation process. Compared with experiment results, this thermal analysis strategy has good consistency. In addition, a limiting and safe slip speed can be determined based on the demagnetization temperature permanent magnet (PM).

This paper proposes a new dual-sided permanent magnet (DSPM) machine with flux-concentrated U-shaped permanent magnets (PMs) in stator, and consequent-pole PMs in rotor, respectively. The proposed DSPM machine can perform a bidirectional field modulation effect (BFME) to enhance the effective harmonics, and hence improving torque capability. A magneto-motive force (MMF)-permeance based model is employed to reveal the torque production mechanism. The torque contributions of main-order working field harmonics are identified and quantified by employing a hybrid finite element (FE)/analytical method with a unified average torque equation. In order to confirm the merits of the proposed design, the basic electromagnetic characteristics of the proposed DSPM configuration are investigated and compared with those of an existing DSPM machine with stator consequent-pole PM design.Besides, in order to further reduce the cogging torque, a parallel complementary (PC) design is adopted for the final prototyping. Finally, a 6-slot/14-pole-pair prototype is manufactured, and some experimental measurements are carried out to validate the theoretical and FE analyses.

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